How to Pollinate in a Greenhouse: The Complete Guide to Greenhouse Pollination

Growing plants in a greenhouse provides many advantages like protection from harsh weather and control over growing conditions. However, the enclosed environment also eliminates natural pollinators that are essential for fertilization and fruit production. Therefore, greenhouse gardening requires creative solutions to ensure successful pollination.

This comprehensive guide will provide greenhouse growers with techniques and strategies to pollinate plants inside a greenhouse. Whether you want to pollinate vegetables like tomatoes and cucumbers or fruit trees and ornamentals, this article covers various methods, tools, and best practices to implement in your greenhouse.

Key Takeaways

• Pollination is crucial for greenhouse plants to produce fruits, vegetables, and seeds. Natural pollinators like bees have limited access indoors.

• Manual pollination involves hand-transferring pollen between flowers using tools like paintbrushes. It ensures fertilization but is time-consuming.

• Bumblebees are efficient greenhouse pollinators. Hives can be installed to provide thorough, vibratory "buzz pollination".

• Mechanical devices like electric wands imitate pollinators. They efficiently distribute pollen for large operations.

• Diligent daily pollination during flowering ensures continual fertilization. Tracking and troubleshooting issues maintains optimal yields.

Why Pollination is Crucial for Greenhouse Plants

Pollination occurs when pollen grains are transferred from the male part of a flower (stamen) to the female part of a flower (pistil). This transfer of pollen allows fertilization to occur and enables the plant to develop seeds and fruit.

While some plant species are self-pollinating, most plants rely on pollinators like bees, bats, birds, and butterflies to carry pollen from one flower to another.

When growing plants in an enclosed greenhouse environment, natural pollinators have limited access. Indoor conditions like low humidity and inadequate air circulation can also inhibit pollen dispersal.

Without successful pollination and fertilization, plants will not produce fruit or seed. For greenhouse owners interested in harvesting vegetables, fruits, seeds, or flowers, ensuring adequate pollination is essential.

Some key reasons greenhouse plants need assisted pollination include:

• Lack of natural pollinators indoors
• Environmental challenges like low humidity and poor airflow
• Maximizing fruit and seed production
• Obtaining quality yields
• Achieving complete pollination in self-incompatible plants

Types of Pollination Strategies for a Greenhouse

When growing in a greenhouse, the two main options for achieving pollination are natural methods and assisted pollination.

Natural Pollination

Taking advantage of whatever natural pollinators are able to access the greenhouse is the most hands-off approach. 

Attracting natural pollinators is a chemical-free way to improve greenhouse pollination. Native bees, flies, beetles, and other insects may enter through vents and cracks. Support populations by:

Planting Nectar-Rich Flowers

Grow pollen and nectar plants inside and around the greenhouse to feed pollinators. Good options include:

• Herbs: Lavender, basil, thyme, oregano, dill.
• Annuals: Cosmos, zinnias, sunflowers, marigolds.
• Native wildflowers: Milkweed, asters, goldenrod, coreopsis.

Provide Nesting Sites

• Leave areas of undisturbed soil and stems for ground-nesting bees.
• Set out bundles of hollow sticks or reeds for stem-nesters.
• Install solitary bee houses on greenhouse walls or adjacent structures.

Open Vents and Doors

• Allow openings for pollinators to enter, especially on warm sunny days.
• Set up screens or barriers to prevent insect pests.

With a pollinator-friendly setup, you can increase natural greenhouse pollination free of cost.

However, relying solely on natural pollination is often inadequate for greenhouse growth. You'll have to find other methods for pollinating in a greenhouse.

Assisted Pollination

To ensure effective pollination in a greenhouse, most growers need to implement assisted pollination techniques. Common options include:

1. Manual Pollination

Also called “hand pollination”, this method involves manually transferring pollen from the male to female flower parts using tools.

For plants like tomatoes, cucumbers, peppers, and squash, the process involves:

• Identifying male and female flowers - male flowers contain stamen which produces pollen, and female flowers contain pistils which catch and transfer pollen for fertilization.
• Collecting pollen from male flowers by removing the stamen or tapping above a collection tool like a paper plate or plastic spoon.
• Transferring the pollen to the female flowers by brushing or tapping the pollen over the pistol stigma.

Tools used for manual pollination include:

• Feather or artist paint brush
• Cotton swab
• Plastic spoon
• Specified pollination wand or electric vibrating wand

Manual pollination is highly effective but requires diligently pollinating every flower as it opens. It can be time-consuming for larger greenhouse grows.

2. Bee Pollination

Bees are extremely efficient greenhouse pollinators. Bumblebees are most commonly used, as they can thrive year-round in enclosed environments.

Key benefits of bumblebee pollination include:

• Active from early spring through late fall.
• Able to fly in cooler temperatures.
• Buzz pollination thoroughly vibrates flowers.
• Increased yields compared to manual pollination.

Bumblebee hives can be purchased and installed in greenhouses to supplement natural populations. For best results:

Select the Right Hive

• Choose a commercial hive with adequate bees for the growing area.
• Opt for a hive with a Colony Irrigation System (CIS) to detect and prevent overheating.

Place Hives Properly

• Position hives 1-3 feet off the ground in a central location.
• Protect from direct sunlight, rain, and chemical applications.

Manage Bee Populations

• Supplement with additional hives once initial flowers appear.
• Remove hives before pesticide use and when blooming slows.
• Provide nectar plants like asters, clover, or fragrant herbs.

With proper installation and care, bumblebees offer an efficient pollination solution.

3. Mechanical or Pneumatic Pollination

Battery-powered tools like vibrators, dusters, or blowers can be used to dislodge and distribute pollen in enclosed areas.

Popular options include:

• Electric toothbrushes or facial massagers: The vibrating heads release pollen when touched by flowers.
• Battery fans or blowers: Used to blow pollen between rows of plants.
• Feather/artist dusters: Made of soft bristles to gently brush pollen onto stigmas.

Though more expensive, these device pollination increase efficiency and are useful for larger operations.

For the best results, pollinate at the ideal time:

• Morning hours when pollen is most viable and stigmas are receptive.
• Daily during the flowering period to ensure continual pollination.
• Midday for peppers, to avoid blossom drop

Step-by-Step Guide to Pollinating Greenhouse Plants

Once you’ve selected a suitable pollination method(s), following these steps will help maximize successful fertilization:

1. Prepare the Greenhouse

Make any adjustments needed to facilitate pollination:

• For bees, install hives/nesting boxes and water sources
• Set out collection tools if manually pollinating
• Obtain mechanical pollination devices
• Place flowering plants around access doors/vents to attract natural pollinators
• Prune extra foliage which can block pollinators' access to flowers

2. Monitor Flowering and Pollen Release

• Check each plant daily for open flowers requiring pollination.
• For manually pollinating, note when male flowers open and begin releasing pollen.

3. Pollinate Female Flowers

• Identify female flowers by locating the pistil in the center of the blossom.
• Use the chosen pollination methods to transfer pollen to the stigma of each open female flower.

4. Record Progress

Note which plants have been manually pollinated or bee/device pollinated each day.

5. Repeat Daily

Check for newly opened female flowers each day. Pollinate all new blossoms following the methods used.

6. Provide Aftercare

• Keep pollinators well-fed. Refill bee feeds and nectar plants for natural pollinators.
• Remove any flowers that have been successfully pollinated.
• Water and weed plants regularly for optimal growth.

Proper technique and diligent repetition will result in thorough greenhouse pollination!

Maintaining Optimal Pollination

Achieving successful initial pollination is just the first step. Ensuring adequate pollination continues throughout the growing season involves:

• Tracking pollination rates - Note the number of resulting fruits/seeds from each plant. Decreasing yields indicate a need for better pollination.

• Troubleshooting issues - If yields drop, inspect flowers and pollinators to identify problems. Address pesticide use, hive health, environmental factors, etc.

• Sustaining pollinators - Keep bees, bats, etc. healthy and consistently accessing flowers. Continue attracting natural pollinators by meeting their habitat needs.

• Adjusting methods - Switch pollination techniques if improved fertilization is needed. Add supplemental bee hives, employ mechanical tools, or start manual pollination.

With attentive management and adaptability, optimal greenhouse pollination is achievable long-term.

The Benefits of Proper Pollination for Greenhouse Owners

Fruits, vegetables, and ornamentals grown in a greenhouse require successful pollination to reach their full potential. The advantages proper pollination provides include:

• Increased Yields - With thorough pollination, plants produce more flowers and fruit. For greenhouse owners, bigger harvests mean higher profits.
• Enhanced Quality - In addition to bigger yields, effective pollination improves fruit/vegetable size, flavor, shelf life, and more. Complete pollination means premium quality crops.
• Reliable Production - Careful greenhouse pollination combats the sporadic yields caused by relying solely on natural pollinator access. Growth is consistent year-round instead of seasonal.
• Maximized Profits - The combination of higher volumes, improved quality, and dependable production leads to greater profits for greenhouse growers.
• Effective Seed Production - For operations harvesting seeds or growing seedling crops, adequate pollination is imperative or seeds will not form.

Careful attention to greenhouse pollination pays dividends for growers seeking the best quantity and quality from each crop!

Conclusion

Pollination inside a greenhouse requires some extra effort, but the rewards are plentiful. Assisted pollination ensures plants can achieve complete fertilization and reap the ensuing benefits.

While pollinating within an artificial environment presents challenges, the solutions outlined above provide a roadmap to get the desired results. With deliberate techniques, an attentive process, and adaptive management, greenhouse owners can achieve successful pollination allowing their plants to fully flourish.

For those looking to set up a new greenhouse, be sure to review our comprehensive greenhouse buyer's guide to help select the right structures and equipment to facilitate excellent growing conditions and pollination. With the proper setup and these pollination best practices, your greenhouse plants will thrive!

FAQs

What challenges can occur with pollination in a greenhouse?

Pollination in a greenhouse can present several challenges. One common issue is controlling temperature and humidity which are crucial for proper pollination. Unfavorable conditions can restrict the action of bees and other pollinators. Also, pollination may become difficult for plants hidden inside the greenhouse, out of reach of pollinators from outside the greenhouse.

Do all plants in the greenhouse need pollination?

Not all plants in your greenhouse need pollination. Some plants are self-pollinating plants and can produce fruit or seeds without the need for pollinators. However, plants that rely on the transfer of pollen for fruit sets will require pollination, and bees play an essential role in this process. Pollination ensures the production and health of such plants.

How do bumble bees differ from other bees in terms of greenhouse pollination?

When it comes to greenhouse pollination, they are considered much more efficient than other bees. In contrast to honey bees, they are not distracted by outside sources of nectar and pollen, leading to an increase in pollination activity within the greenhouse. Bumble bee pollination is especially beneficial for plants like tomatoes that require a particular way of pollination.

How does the size of the greenhouse affect pollination?

Regardless of size, you can adequately pollinate plants in a greenhouse. In a small greenhouse, manual pollination might be easier due to the limited space. However, in a larger setup, attracting natural pollinators or using a pollination device may be more efficient. Also, controlling the airflow becomes more important in a larger greenhouse for pollination.